Simethicone Pre-Treatment With Polyethylene Glycol and Bisacodyl Combination Preparation in an Effort to Improve Bowel Wall Visualization

Abstract

Introduction: The presence of small air bubbles and foam can lead to impaired endoscopist view and diminish the diagnostic accuracy of a colonoscopy. Few studies have evaluated the efficacy of simethicone as an anti-foaming component with bowel preparations. This has been particularly noted to be of concern with the switch to lower volume polyethylene glycol (PEG) and bisacodyl combination preparations. Methods: We designed a prospective, randomized, multi-center, double blinded study to evaluate the use of simethicone formulation with split regimen, low volume PEG-Bisacodyl combination bowel preparation for outpatients undergoing elective colonoscopies. 124 adults are allocated into the treatment arm consisting of 200 mg of liquid simethicone and 126 adults are allotted to the control arm containing placebo water preparation to be mixed along with the bowel preparation. Intra-luminal bubbles scale is used as a primary endpoint defined by the percentage of the mucosa obscured by bubbles as seen by endoscopists during the procedure and whether intervention with simethicone infused saline wash is required. Secondary outcomes include the evaluations of adequacy of bowel preparation using the validated Boston Bowel Preparation Scale (BBPS), the number and types of polyps/masses detected, cecal insertion time, withdrawal time, and patient reported adverse effects. In an effort to reduce and measure inter-observer variability, 10 gastroenterologists are provided imaging examples of the Bubbles Scale and the Boston Bowel Preparation Scale for reference during rating and intermittently assessed through grading various images of intra-luminal bubbles. Results: The incidence of high levels of bubbles (Grade III and IV, less than 75% of the mucosa cleared of bubbles/foam requiring intervention with simethicone infused saline wash) is 5% and 30% respectively in simethicone vs. placebo group (P=<0.001). BBPS total score is 7.42 (+/- 1.62) simethicone and 7.29 (+/- 1.40) with the placebo group (P=0.474). Polyp detection rate is 1.51 in simethicone group vs. 1.13 in control group (P=0.825). Conclusion: Although recruiting has been completed, the study is in progress and 139 out of 250 participants have undergone endoscopies. Remaining participants are scheduled for the study duration ending in July 2018. Due to the fewer number of existing studies and lack of significant data, simethicone has not been incorporated in most commercially available bowel preparations for its anti-foaming properties.516_A Figure 1. Bubbles Scale516_B Figure 2. Logos